The present invention relates to an apparatus and method for fluid analysis. Particular embodiments of the present invention relate to on-board analysis of multiple attributes of operating machine fluids necessary for the determination of machine health.
It is well known that chemical and physical analysis of a machine fluid can provide information about the condition of the fluid as well as the wear status of the machine in which the fluid is used. Machine fluid analysis is widely used for determination of lubricant condition, lubricant contamination and wear status in engines, drive components and hydraulic systems in fleet or industrial service. For example, lubrication oil analysis is widely used for railroad engines and is conducted by the military on most motorized equipment including aircraft and naval engines and lubricated drive components. In industry, commercial fluid analysis providers offer fluid analysis service for engine and drive train lubricants as well as hydraulic fluids.
Locomotive engine manufacturers such as General Electric (GE) and General Motors Electro-Motive Division (EMD) promulgate recommended limits for wear elements as determined by spectrographic analysis of lubrication oil samples. Manufacturers and railroad operators also set limits on such parameters as water or fuel dilution of lubricating oil, soot and pentane insolubles (compounds in oil that do not dissolve in pentane). These limits indicate when maintenance is required to prevent impending component failures that may result in severe and expensive engine damage. Properly interpreted, the analytical data can also indicate specific maintenance operations that need to be performed on the engine.
Traditionally, an oil sample has been taken from the lubricant reservoir on the engine being analyzed, and each of these parameters was then measured in the laboratory by different instruments for different purposes. Viscosity is measured with a viscometer and provides an indication of possible dilution of the oil by fuel or water. Viscosity can also indicate oil degradation from heat or oxidation. Chemical degradation of the oil (e.g., oxidation, nitration) is commonly determined by infrared (IR) spectrometric analysis, which may also be used to infer total acid number (TAN) and total base number (TBN) for the oil. Water in the oil may also be detected by IR analysis. Slow coolant leaks into the lubricating oil system may be detected by quantitative analysis of boron, chromium or other elements present in the coolant water as salts. Elemental analysis is typically accomplished by atomic emission spectrometry (AES) or other atomic spectroscopy methods, but may also be accomplished by X-ray fluorescence (XRF). Such analyses provide an indication of component wear according to the type and amount of metal(s) in the sample.
Monitoring of machine fluids to specifically determine the parameters described above presently requires that samples of the machine fluid(s) be obtained and sent to a laboratory for chemical and physical analysis. However, the machines for which laboratory analysis is most valuable are often mobile, and may at any time be in remote locations, making sampling and laboratory analysis impractical on a frequent or regular basis. Moreover, the small sample amounts obtained for analysis may not be representative of the bulk machine fluid, and analyses in the laboratory require a day or more to perform. The logistical impracticality of laboratory analysis is overcome in practice with scheduled maintenance and service for machines. Such routine maintenance schedules are designed so that machine fluid change-out occurs prior to the time damage to the machine may result, and are scheduled to ensure that they provide sufficient leeway before a problem is projected to occur. It is believed that the frequency of maintenance and service could be reduced by the use of more frequent and regular machine fluid analysis.
Additionally, there are environments wherein immediate indicators of machine health are critical. As an example, when an engine on a helicopter or airplane fails, the result to passengers can be disastrous. An indication to the pilot of a failing engine, prior to actual engine failure, may provide sufficient time to either save the engine from destruction, or provide time for the pilot to safely return to the ground under power.
On-board or in situ machine fluid analysis has been investigated with several proposed approaches. For example, Voelker et al (U.S. Pat. No. 5,789,665) described a method and apparatus for determining deterioration of lubricating oils by measuring electrical properties of a polymeric matrix or by exploiting volumetric change behavior of the polymeric matrix in the form of beads. Disadvantages of this approach include that it responds only to a single parameter (free water) but does not quantify the free water, and there is a need to replace used polymer beads.
Freese et al. (U.S. Pat. No. 5,604,441) relies on measurement of changes in dielectric properties of a lubricant (oil) in a changing magnetic field. The change in dielectric properties indicates a change in oil condition. Dielectric constant is non-specific and at best may provide an indirect indication of oil degradation. The magnetic field is also used to attract and quantify ferromagnetic particles.
Finally, Boyle et al. (U.S. Pat. No. 5,964,318) designed a system to measure the level and quantity of lubricant in an engine lubricant reservoir. On-board in situ sensors are provided to measure the quantity of lubricant in the system, as well as the quality (temperature, pressure, dielectric and/or viscosity). If the quality drops below a predetermined level, the system diverts a portion of the lubricant to a reservoir for storage or reintroduction as a fuel additive, and a coincident addition of fresh lubricant to the system to maintain the desired level of lubricant. However, the apparatus/process disclosed in the ""318 patent is a totally self-contained system; it does not provide an indication to those remotely monitoring engine health of the current status of lubricant within the enginexe2x80x94it is solely an internally-monitored lubricant quality indicator.
The above-cited patents describe measurements that do not provide to remote observers information sufficient to determine the wear status of the machine containing the measured fluid, and so they cannot be used in lieu of standard laboratory oil analysis. In particular, the above-cited patents do not describe a system that allow real time and remote assessment of machine condition, because they lack the capability to determine wear metal concentrations.
On-board measurement and analysis of operational parameters, including determination of fluid levels and fluid and gas temperatures and pressures for a gas turbine engine, has been described (Greitzer et al, 1994). These authors described the use of sensors and artificial neural network software to analyze engine operational status and condition. This approach has been termed machine health monitoring. However, these authors did not attempt to measure standard laboratory analysis parameters for any machine fluid.
Hence, there remains a need for in situ or on-board analysis of machine fluid that provides information similar in nature and utility to that obtained from standard laboratory machine fluid analysis.
The present invention is an apparatus and method for analyzing a fluid used in a machine or in an industrial process line. In one embodiment of the present invention, the apparatus has at least one meter (or sensor) placed proximate a machine and in contact with the machine fluid for measuring at least one parameter related to the machine fluid. The at least one parameter is a standard laboratory analysis parameter. The at least one meter includes, but is not limited to, viscometer, element meter, optical meter, particulate meter, and combinations thereof. Additionally, the results of this machine fluid analysis are made immediately available to remote observers of machine-related system health, whether the analyzed machine fluid is engine lubricant, hydraulic fluid, fuel, coolant fluid, or the like.
As used herein, xe2x80x9cproximatexe2x80x9d means on or near.
As used herein, xe2x80x9cmeter . . . in contact with the machine fluidxe2x80x9d means that the machine fluid passes to the meter(s) or sensor(s) under pressure of the machine. This is in contrast to collecting a sample in a separate container and introducing the sample to the meter(s) independently of, or separate and distinct from, the machine and the machine pressure.
As used herein, the term or phrase xe2x80x9cstandard laboratory analysis parameter(s)xe2x80x9d refers to parameters specified for direct determination of fluid or machine condition. More specifically, standard laboratory analysis parameter includes, but is in no way limited to, viscosity, low viscosity and high viscosity; pentane insolubles; soot, additive package (presence of chemical additives used to improve lubrication characteristics), oxidation or oil polymer breakdown products, nitration, sulfation, fuel dilution, water concentration; or concentration of specific elements including, but not limited to, iron, lead, copper, silicon, chromium, aluminum, silver, and zinc. In contrast, a non-standard parameter would be an indirect measure including, but not limited to, dielectric constant, polymer swelling, and combinations thereof and are specifically excluded from xe2x80x9cstandard laboratory analysis parameterxe2x80x9d.
As used herein, xe2x80x9cmachine fluidxe2x80x9d means any fluid used in the process of operation of machinery. Examples include, but are not limited to, oil, engine oil, differential oil, transmission fluid, hydraulic fluid including, but not limited to, power steering fluid, brake fluid, and hydraulic cylinder fluid, and combinations thereof whether petroleum-based or synthetic; electrical fluid including, but not limited to, battery fluid, condenser fluid (e.g. PCB), and electrochemical electrolyte; refrigerant; cutting fluid; fuel; coolants including water; and combinations thereof.
As used herein, the phrase xe2x80x9cremote observer of machine healthxe2x80x9d means another machine or an individual outside the monitored engine or machine itself, which is programmed or trained to recognize non-routine measurements transmitted by the meter in contact with the machine fluid. The remote observer may be a machine programmed to issue a warning signal if a significantly non-routine measurement is transmitted, or it may be a person, such as the machine operator.
An advantage of the present invention is that it provides to a remote observer of machine health an accurate on-board determination of machine fluid and/or machine condition because of the use of the standard laboratory analysis parameter. Further advantages include real-time machine fluid data capture and machine fluid data capture for remote locations of the machine.
In a preferred embodiment of the present invention, a plurality of standard laboratory analysis parameters is measured or obtained thereby permitting real-time and/or remote assessment of machine and/or machine fluid condition while the machine is in or available for service. An advantage of this preferred embodiment is more timely and cost effective service based on machine condition rather than more traditional service and maintenance based simply on the length of time a machine has been operating.
It is an object of the present invention to provide an apparatus on a machine and in contact with a machine fluid for analysis of the machine fluid by measuring at least one standard laboratory analysis parameter.
It is a still further object of the present invention to provide a system for determining on-board real time parameters of machine fluid systems relating to the health of a machine whereby a plurality of sensors are placed proximate the machine such that a plurality of standard laboratory analysis procedures are determined on-board the machine, with such characteristics being transmitted to a remote observer of machine health.
While an embodiment of the present invention is disclosed with particular reference to an engine lubricant system, it is equally applicable to numerous other systems that determine machine health as well as to industrial fluid processes that would benefit from the types of in situ fluid analysis disclosed herein. Likewise, the invention is not limited to particular apparatuses and methods disclosed herein, but is rather broad enough to encompass the entire system regardless of the particular apparatus utilized.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements.